1. Field of the Invention
The present invention relates to a control apparatus of a direct injection internal combustion engine mounted in a vehicle as one power source, and more particularly to a control apparatus of a direct injection internal combustion engine used when the internal combustion engine is stopped, as in an idling stop time.
2. Description of the Related Art
In recent years, from a viewpoint of emission reduction and improvement in fuel efficiency, an idling stop vehicle and a hybrid vehicle have been known. The hybrid vehicle, for example, is capable of automatically stopping its engine when in a state in which the efficiency of the engine declines (e.g., when the vehicle is stopped or driving at a low speed) and running solely using the driving force of an electric motor.
Meanwhile, mainly to improve the fuel efficiency, a direct injection internal combustion engine (a direct injection engine) which directly injects fuel into a combustion chamber has been practically used as a spark-ignition engine. The direct injection engine can improve filling efficiency and increase a compression ratio. Therefore, the direct injection engine is expected to perform highly efficient combustion, compared with a port injection engine.
The direct injection engine has an advantage of directly injecting fuel into the combustion chamber. By using the direct injection engine with this advantage, the idling stop vehicle can obtain prompt restart performance and improved precision in torque control when starting the internal combustion engine which is essential for controlling the hybrid vehicle.
As an example of such application of the direct injection engine to the hybrid vehicle, JP, A 2003-065105 (hereinafter referred to as a Patent Document 1), for example, describes a direct injection engine which only injects fuel into a cylinder under a compression stroke upon satisfaction of an engine stop condition, so that the restart performance of the hybrid vehicle upon discontinuation of the idling stop state is improved.
Usually, when the engine is stopped, fuel cut and ignition cut are carried out by an ignition switch-off operation performed by a driver. As a result, fuel adhered to an intake port remains in the combustion chamber or in the intake port in some cases.
In light of the above, JP, A 2003-172188 (hereinafter referred to as a Patent Document 2), for example, describes a port injection engine which, when the engine is stopped by the ignition switch-off operation performed by a driver, advances timing of performing the port injection for prolonging a fuel evaporation time and continuing to perform ignition control, so that as much fuel as possible is combusted to reduce an amount of residual fuel.